This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. PD TIKHONOV is a software package for extracting the pair distributions from pulsed ESR experiments using the Tikhonov regularization method. A service request has been received from Dr Budamagunta to use the software to analyze their DEER data of protein samples.